There are people who are great at solving problems in business, technology, social work and other fields. Give them a problem, and they will charge at it, bound over obstacles and break down barriers, until the solution is all that is left. For such people, solving problems is like a drug that leaves them feeling high.
The problem with drugs is that the high you get never lasts, and is never as satisfying as the previous fix. Hence these problem junkies end up seeking bigger problems. Too often, the really big problems are tied up in politics - whether at a company level or in the machinery that is government.
Eventually some problem solving addicts get into politics, thinking that they can apply their problem solving skills to bigger problems. However, politics doesn't solve problems. Politics is about pontificating, justifying, posturing, and rationalising; it is not about problem solving. Faced with this reality, those who enter politics have two choices: become a good politician and forget about the big problems, or leave politics and go back to solving problems that can actually be solved.
Worse than the realisation that politics is an end in an of itself, not a means to one, is the realisation that getting into politics is like joining the mafia - it's not easy to leave. When people get into politics with good intentions, they either get disillusioned or absorbed by it. Then, sadly, the problem solvers unwittingly become part of the problem.